Cyanine dyes containing a 3,4-dihydroisoquinoline nucleus



Patented Oct. 10, 1 950 2,525,520 CYANINE DYES CONTAINING A 3,4-DIHY- DROISOQUINOLINE NUCLEUS Leslie G. S. Brooke! and Robert H. Sprague, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey N Drawing. Application March 20, 1948, Serial No. 16,146'

This invention relates to cyanine dyes containing a 3,4-dihydroisoquinoline nucleus and to a process for preparing such dyes.

l-methyl-3,4-dihydroisoquino1ine is a known base, having been described by Spath et al., Ber. 63, 134 (1930). nary salts of this base by heating the base with alkyl salts. These quaternary salts, we have found, can be condensed with trialkyl orthoformates to give carbocyanine dyes, and with other substances to give still other cyanine and styryl dyes. This is surprising, since alkyl quaternary salts of l-methylisoquinoline cannot be condensed with trialkyl orthoformates to give carbocyanine dyes. See the copending application of F. L. White and L. G. S. Brooker, Serial No. 672,340, filed May 25, 1946 (now United States Patent 2,466,523, dated April 5,1949). Moreover, 1 methyl- 3,4 dihydroisoquinoline quaternary salts donot condense with trialkyl orthoaceta-tes or orthopropionatestogive carbocyanine dyes.

It is, accordingly, an object of our invention to provide new cyanine and styryl dyes containing a 3,4-dihydroisoquinoline nucleus. It is a further object to provide a process for preparing such dyes. Still other objects will become apparent hereinafter.

In accordance with one embodiment of our invention, we condense a trialkyl orthoformate with a l-methyl-3,4-dihydroisoquinolinealkyl quaternary salt selected from those represented by the following general formula:

wherein R represents an alkyl group, i. e. an alcohol radical, e. g. methyl, ethyl, n-propyl, n-butyl,. isobutyl, n-amyl, isoamyl, p-hydroxyethyl, y-hydroxypropyl, B-methoxyethyl, p-ethoxyethyl, allyl, benzyl (phenylmethyl) fl-phenylethyl, p-carboxyethyl, carboxymethyl, a-carboxyethyl, y-carboxypropyl, e-acetoxyethyl, y-acetoxypropyl, carbomethoxymethyl, carbethoxymethyl, e-carbomethoxyethyl, fl-carbethoxyethyl, etc. and X represents an anion, e. g. benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, chloride, bromide, iodide, perchlorate, thiocyanate, sulfamate, acetate, propionate, butyrate, etc.

As trialkyl orthoformates, the following are examples: trimethyl orthoformate, triethyl orthoformate, tri-n-propyl orthoformate, tri-nbutyl orthoformate, n-propyldiethyl orthoformate, triisoamyl orthoformate, etc.. The condensations are advantageously effected in pyridine.

The dyes obtained by these condensationscan be represented by the following general formula;

We have prepared, alkyl quater- 6 Claims. (Cl. 260-24055) Hi6 :OH-OH=OH EH, @2041 V boon;

1'. R X wherein R and X have the values given above.

We have found that the 1-methyl-3,4-dihydroisoquinoline alkyl quaternary salts can be condensed with cyclammonium quaternary salts containing a thioether group in a, reactiveposition (i. e. the alpha .or, gammaposition), e. .g'. cyclammonium quaternary salts having the following general formula: 1 III. Q\

wherein X has the value given above, R1 represents an alkyl or aryl group, e. g. methyl, ethyl, n-propyl, n-butyl, benzyl, phenyl, p-chlorophenyl, [3-naphthyl, eto., R2 represents an alkyl group, e. g. those givenabove under: R, n represents a positive integer of from'l to 2, and Q represents the non-metallic atoms necessary to complete a hetero'cyclic' nucleus containing. from 5 to 6 atoms in the heterocyclic ring. Typical of these thioether compounds represented by Formula III- are: 2 -methy1mercaptobenzothiaz'ole. methov p -toluenesulfonate,' 2- phenylmercaptoquinoline ethiodide, z-ethylmercapto 5,6 dimethoxybenzothiazole' etho -'p,- toluenesulfonate, 2-methylmeroaptobenzoxazole etho-p-toluenesulfonate, 2-methylmercapto-5,6-'

propylamine, triisoamylamine, N-methylpiperidine, N-ethylpiperidine, 'triethanolamine, etc. Diluents may also be used, e. g. lower aliphatic alcohols, for instance, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, etc.

The-monomethine d-yes obtained by these condensations can be represented by the following general formula:

Q 7 a m CH=CH N HzC;N\ R4 wherein R and X have the values given above and R3 and R4 each represents an alkyl group.

We have also found that the l-methyl-3,4-dihydroisoquinoline alkyl quaternary salts can be condensed with pyrrole carboxaldehydes selected from those represented by the following general H wherein R, R5, R6 and X have the values given above.

The following examples will serve to illustrate further the manner of obtaining our new dyes and the alkyl quaternary salts of 1-methyl-3,4- dihydroisoquinoline.

Example 1. 2,2'-diethyZ-3,4,3',4'-tetrahydro- 1,1'-isoquinocarbocyanine perchlorate 1.45 g. ('1 mol.) of 1-methyl-3,4-dihydroisoquinoline and 2.0 g. (1 mol.) of ethyl p-toluenesulfonate were heated together for one hour at 110 C. The viscous product was washed by decantation with 25 cc. of ether. 1.5 g. (2 mols.) of ethylorthoformate and 20 cc. of pyridine were added and the mixture boiled under reflux for 30 minutes. The red solution was cooled, diluted with 200 cc. of ether and chilled to 0 C. The ether layer was decanted off and the sticky residue dissolved in 10 cc. of absolute ethyl alcohol. The dye was precipitated by addition of an aqueous solution of sodium perchlorate. The dye was collected on a filter, washed on the filter with water and dried. The yield of red crystals was 1.8 g., '79 per cent. After recrystallization from methyl alcohol cc. per gram) the product was obtained as red needles with a bright reflex melting with decomposition at .215-216 C. Yield 1.5 g., 66 per cent.

Example 2.1-methy l 3,4 dihydroisoquinoline metho-p-toluenesulfonate 3.8 g. (1 mol.) of 1-methyl-3,4-dihydroisoquinoline and 4.9 g. (1 mol.) of methyl p-toluenesulfonate were heated together at C. for 30 minutes. The crystalline solid product was cooled, crushed under 25 cc. of acetone, chilled to 0 C. and collected on a filter. The product was washed with acetone on the filter and dried. The yield of white crystals Was 8.3 g., 95 per cent. 1

Example 3.-1 methyl 3,4 dzhydroisoquz'noline etho-p-toluenesulfonate Example 4. 2,2-dimethyl-3,4,3,4-tetrahydro- 1,1 -z'soquinocarbocyanine iodide 1.65 g. (2 mols.) of 1-methyl-3,4-dihydroisoquinoline metho-p-toluenesulfonate, 0.75 g. (2 mols.) of ethylorthoformate and 20 cc. of pyridine were boiled together under reflux for 30 minutes. The red solution was cooled, diluted with cc. of ether and chilled to 0 C. The ether was decanted oif and the sticky residue dissolved in 10 cc. of hot methyl alcohol. The dye was precipitated from this solution by the addition of excess sodium iodide dissolved in methyl alcohol and diluiien f t e m ture to 150 cc. wi h w erh 'red crystals of dye were collected .on a :=filter,

washed on the filter with water and acetoneand dried. The yield of red needles of dye was 0.7 g., 61 per cent. After recrystallization from methyl alcohol (20 cc. per gramof dye) the product was obtained as bright red needles melting with decomposition at 263-264 C. Yield 0.45 g., 40 per cent.

Example 5. 1 --dimethylaminostyty l-3,4-dihy- 'droisoquinolmc mcthoperchlor'ate .;and:the dye'dissolved in,10 cc. of hot "methyl alcohol. The dye was precipitatedyas the.perchlorate by addition of excess aqueous sodium perchlorate solution, The alcohol solution was decanteclcff and the dye stirred with 25 cc. of hot absolute ethyl alcohol untilcrystalline. The dye was collected on a filter, washed on the filter with alcohol and dried. The yield of red crystals was 0.4 g., 20 per cent. After recrystallization from absolute ethyl alcohol (100 ,cc. per gram) .theidye was obtained as red crystals melting with decomposition at 154-156 C. Yield 03 .g., per cent.

Example 6. 1-p dimeth zammo'tyr z-Mamydrozsoquinoline methoperchlomte 3 1120 C-CH==OH N(CH3)2 3.45 g. (1 mol.) of 1methyl3,4-dihydroisoquinoline etho-p-toluenesulfonate, 1.5 g. (1 mol.) of p-dimethylaminobenzaldehyde, 2 drops of piperidine and 15 cc. of absolute ethyl alcohol were boiled together under reflux for 45 minutes. A solution of 2.25 g. (1 mol.-l-50 per cent excess) of sodium iodide in 5 cc. of methyl alcohol was added and the mixture was chilled to 0 C. The dye was collected on a filter, washed on the filter with acetone and water and dried. The yield of red crystals was 1.8 g., 42 per cent. After recrystallization from methyl alcohol (58 cc. per gram) the dye was obtained as red needles with a green reflex melting with decomposition at 240- 242 C. Yield, 1.3 g., 30 per cent.

Example 7 .-1 EthyZ-2',5 -d1 methyl-1 -phenyZ-3, 4-dihydro-1-isoquino-3-pyrr locyanine iodide 3.45 g..(1'mol) of 1-methyl-3,4-dihydroisoquinvoline etho-p-toluenesulfonate, 1175 g. .(limol) of 2,5-dimethyl-1-phenyl-3 pyrrolecarboxaldehyde, 2 drops of piperidineand '15 ccuof absolute ethyl alcohol were boiled together under reflux :for .45 minutes. The solution was cooled, diluted with 150 cc. of ether and chilled to 0 C. The ether solution was decanted from the sticky precipitate of dye and the .dye dissolved in 15 cc..of hot methyl alcohol. A solution of 2.5 g., 1 mol.',-\- per cent excess) of sodium perchlorate in 10 cc. of hot methyl alcohol was added and the mixture chilled to 0 C. The dye was collected on a filter, washed on the filter with water and dried. The yield of yellow *crystals was 1.3g, 29 per cent. After recrystallization from absolute ethyl alcohol (20 cc. per gram) the dye was obtained as heav yellow crystals melting with decomposition at 193-195 C. Yield 1.0 g., 22 per cent;

Example 8. 1 ',2-dzethyl-3,4- dihydm-l -is0quin0- 2'-cyanine iodide 3.45 g. (1 mol.) of 1-1nethyl-3,4-dihydroisoquinoline etho=ptoluenesulfonate, 4.4g. (1 mol.) of 2-phenyl-mercaptoquinoline etho-p-toluenesulfonate, 1.0 .g. (111101.) of triethylarmine and 25 cc. of absolute ethyl alcohol were boiled together under refiuxfor 15 minutes. The dye was precipitated from the red solution by addition of 3.0 g. (1 mol. 100 per cent excess) of sodium iodide dissolved in 15 cc. .of hot methyl alcohol. The dye was collected on a filter, washed onthefilter with Waterand a-cetoneanddried. The yield of red crystals was.2.5 g., 55 per cent. After recrystallization from methyl alcohol (75 cc. per gram) the dye was obtained as red crystals with a green reflex which had a melting point of 2'70- 272 0. Yield 2.0 g., 44 per cent.

In a manner similar to that shown in the foregoing examples other dyes of our invention can be prepared.

The pyrrole carboxaldehydes employed herein can be prepared by condensing formamide with a pyrrole base selected from those represented bythe following general formula:

VIII. HC-CH wherein R5 and R6 have the values given above, in the presence of phosphorus oxychloride, according to the method of Nenitzescu and Isacescu, Bull. Soc. Chim. Roumania 11, (1929). Details of this preparation are also given by Brooker and Sprague, Jcur. Am. Chem. Soc. 67, 1869 (1945), and b Brooker and Sprague in United States Patent 2,409,612, dated October 22, 1946. The pyrrole bases of Formula VIII can be prepared according to the process of Lions et al., Proc. Royal $00., New South Wales 71, 92 (1937) The dyes disclosed herein sensitize photographic silver halide emulsions. Some, e. g. the dyes of Examples 5, 6 and '7 are bleached by the ordinary alkaline photographic developers and hence are useful in preparing bleachable filter layers for photographic elements.

What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. The dyes containing a 3,4-dihydroisoquinoline nucleus which are represented by the followin general formula:

wherein R represents a primary alkyl group of the formula CmH2m+l wherein m represents a positive integer of from 1 to 4 and X represents an anion.

2. The dye which is represented by the following formula:

3. The dye which is represented by the following formula:

4. A process for preparing a carbocyanine dye comprising condensing a 1-methyl-3A-dihydroisoquinoline alkyl quaternary salt selected from those represented by the following general formula H; o-on,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,108,484 Hamer Feb. 15, 1938 FOREIGN PATENTS Y Number Country Date 576,532 Germany 1933 OTHER REFERENCES Mills, J. Chem. Soc. (1922), pages 2724-2734. 

1. THE DYES CONTAINING A 3,4-DIHYDROISOQUINOLINE NUCLEUS WHICH ARE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 